1. Field of the Invention
This invention relates in general to subsea drilling, and in particular to a test tool for testing a diverter system on a drilling rig.
2. Description of the Prior Art
In subsea drilling of the type concerned herein, a marine riser assembly will extend from the subsea well to an offshore drilling rig. A diverter system is mounted to the drilling rig. The diverter system is connected to the upper end of the marine riser. The diverter system has fluid inlets/outlets or ports, one of which allows drilling mud returning up through the marine riser to flow to a mud pit area for cleaning and recirculation. At least one other port leads to a diverter line for discharging any gas that might flow up the marine riser during shallow drilling.
The diverter system contains a packer assembly similar to that in a blowout preventer. This packer assembly includes a rubber packer element that can be closed around the drill pipe in case gas begins flowing up the marine riser during shallow drilling. In that event, valves can be actuated to divert the gaseous fluid out through a diverter line away from the drilling rig.
At the present, there is no means to test whether or not the diverter packer element and associated flow control valves are properly sealing. If fluid test pressure is applied to the diverter system with the packer element closed around the drill pipe, it would apply pressure to the earth formation, which is not desirable.